textproduct: Rapid City

KEY MESSAGES

- Increasingly active convective pattern will develop this week and persist through the upcoming weekend - Isolated severe thunderstorms possible Wednesday afternoon/evening in the far southwest - Slight risk of severe thunderstorms Thursday afternoon/evening, especially west - Saturday could be quite active, but confidence in position of frontal boundaries and upper support/thermal ridge on the low side

DISCUSSION

(This Evening Through Tuesday) Issued at 1233 PM MDT Tue Jun 23 2026

18z surface analysis had cold front well south/east of the CWA with weak high from MT into western SD. Diurnal heating fluffing some CU here and there per 0.5km visible satellite loop, but atmosphere is short on fuel per 18z KUDX sounding. Better looking south of the CWA. Water vapour loop had upper low over south central Canada supporting west/northwest flow aloft over the northern Plains.

Through tonight, some shra/TS may develop, but best buoyancy south of CWA so not expecting organized convection. Lows tonight will be near guidance.

Wednesday, shortwave moves across MT/Dakotas during peak heating with plenty of shear, but only 500-1000J/kg mean MUCAPE across the far southwest. Isolated severe thunderstorms may occur with the latest CAMS indicating strongest updraft/helicity tracks south of the CWA. Temperatures will remain on the cool side given forecast lower tropospheric soundings.

Thursday looks more interesting as deep upper low/trough drops into southwest Canada/northwest CONUS turning our upper flow west/southwest. Lee trough develops with robust southeasterly return flow over the CWA bringing richer boundary moisture. Barring significant stratus development (guidance/pattern hints this will occur), combination of buoyancy/shear across the western half of the area will be sufficient for a slight risk of severe thunderstorms.

Friday, upper low deepens over the northwest CONUS with southwest flow aloft developing, but with height rises over the northern Plains which may help to suppress organized convection. If something goes, active storms will occur. Saturday/Sunday, upper low ejects northeast with a favorable setup for active/severe thunderstorms each day. Of course, details way too far out to get into, but subjective pattern recognition suggests a busy weekend.

AVIATION

(For the 18Z TAFS Through 18Z Wednesday) Issued At 1111 AM MDT Tue Jun 23 2026

Transient MVFR ceilings will continue across portions of NE WY, the Black Hills, and south-central SD through 20z this afternoon. Otherwise, VFR conditions are expected with broken ceilings around 5000-10000 feet AGL. Isolated showers/storms are possible this afternoon across the Black Hills.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.